gilbert



2 Sheets-Sheet 1.

(No Model.)

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No. 478,589. Patented Jul'y 12,A 1892.

Inventor E 2 S S C (N0 Model.) V2 sheets-sheet 2.' W. H. GILBERT. DENTAL CHAIR.

Patented July 12, 1892.

' INVENTOR UNITED STATES PATENT OFFICE.Y

WILLIAM II.v GILBERT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE S. S. WHITE DENTAL MANUFACTURING COMPANY, OF SAME PLACE.

DENTAL CHAIR.

SPECIFICATION forming part Of Letters Patent NO; 478,589, dated July 12, 18.92. Application led March 24, 1890. Serial No. 345,094. (No model.)

To all whom t may concern:

Be it known that I, WILLIAM H. GILBERT, of the city and county of Philadelphia, and State of Pennsylvania,have invented certain new and useful Improvements in Dental Cha-irs, of which the following is a specifica-Y tion.

My invention relates to improvements, as

hereinafter claimed, in chairs of the class Y 1o which are provided with back-pads vertically adjustable independently of the seats thereof; and my object is to provide means by which a chair-back pad may quickly be raised or lowered without altering the position of the I5 seat and firmly held in its adjusted position, While securing a strong, simple, and durable construction of parts.

In the accompanying drawings, Figure l is a View in rear elevation showing all parts of zo a dental chair which it is necessary to illustrate in order to exhibit a suitable embodiment of my invention. Fig. 2 is a horizontal section, on an enlarged scale,'on the line 2 of Fig. 1. Fig. 3 is a side elevation, with parts z 5 in section, on a considerably enlarged scale, showing details of construction; and Fig. 4 shows in perspective the pawl-carrier and lifting-handle of the back-pad carrier detached.

The back-frame A of the chair has upwardlyextending sides B B, having inwardly-projecting guide-ribs C C for engagement with grooves D D at opposite sides of a vertically-adjustable back-pad carrier E. The frame F of the back-pad is secured in usual way to this car- '3 5 rier. Recesses of ratchet-tooth shape, to constitute a detent-rack G, are formed in the rear surface of one of the guide-ribs C of the backframe; or, if preferred, each of the ribs may be provided with a detent-rack G. A pawlcarrier I-I, which also serves as a handle for raising and lowering the back-pad carrier, is provided with a pawl h for engagement' with the datent-racks. Two such pawls would be provided were there two detent-racks.- This pawl-carrier and lifting-handle H is jointed to the back-pad carrier by a pivot I, so as to be capable of a vertical rocking orswinging Inovement. A spring J, connecting the pawl-carrier and the back-pad carrier, acts with a tendency 5o to maintain the pawl-carrier in its normal position-that is,with the pawl engaging the detent-rack and locking the back-pad carrier against movement. The spring, as shown, is fastened at one end to an eyebolt K, screwed into the pawl-carrier, and is engaged at its opposite end with the back-pad carrier, after being passed th rough an opening-in a cross-piece thereof, by means ot' a cross-head 7c, formed by abent rod, to the center of which the spring is secured. To enable the pawl to be moved into 6o operative position, the sides of the back-pad carrier are cut away or recessed, as at L, from their rear surfaces to their guide-grooves, thus permitting the pawl-carrier to come in contact with the guide-ribs of the back-frame, while the pawl engages a recess of the detentrack.

From the above description it will be seen that in raising and lowering the back-pad the hand may be inserted between the opposite 7o sides ofthe back-pad carrier below the spring engaged cross-bar thereof andbeneath the pawl-carrier to grasp and swing it upon its pivot to throw the pawl out of engagement with the detent-rack, vafter which the pawlcarrier serves as a handle for controlling the vertical movement of the back-pad carrier. Upon releasing the pawl-carrier the pawl becomes engaged with its detent-raok to secure l the back-pad in .its position of adjustment. 8c As will readily be understood, the back-pad carrier may be grasped and lifted without catching vhold of the pawl-carrier, the pawl sliding over the detent-rack when the backpad carrier is being so lifted. Y8 5 To brace and prevent the spreading apart of the sides B B of the back-frame, I provide the back-pad carrier with ribs or flanges m m at its opposite'sides. These ribs extend vertically or lengthwise of the carrier and pro- 9o ject slightly rearward from the front Walls of the grooves D D therein, so asV to engage grooves n n, formed in the front surfaces of the ribs O C of the back-frame at right angles with the grooves in the back-pad carrier, with which the ribs O O engage.- In this way, as will readily be understood, the back-frame is in an economical way securely braced against the spreading apart or opening out of its sides.

The ribs m m are shown as secured to the Ioo back-pad carrier by screws but, as is obvious, they may readilybe cast with the carrier; and

as my invention may in other respects be .moditied to some extent-as, for instance, by

omitting the paWl-carryingspringand depending upon gravity to engage the pawl With its detent-rack-I do not Wish to be understood its limiting myself to the precise construction and arrangement of parts herein described in detail.

I claim as my invention- The combination of the chair-back frame provided with the detent rack extending lengthwise thereof, the vertically-adjustable 

